The present invention relates to an improved irrigation or sprinkler system, and more particularly to an irrigation system which operates at maximum efficiency to provide adequate moisture in accordance with the amount of moisture in the soil in a particular area.
When irrigating a large area such as a crop field or lawn, differences in the soil content, drainage, topography and ground moisture at a given time are all factors which determine the amount of water needed to properly irrigate the particular area to a maximum level without over or under irrigating, causing subsequent damage to the plant life. It is well known to provide irrigating systems which are operated by timers and moisture sensors to determine the amount of moisture applied to a particular area. These systems are normally adequate when ambient conditions are within normal ranges, however, more adverse conditions often result in a non-uniform or less than adequate application or overapplication of water. For example, if water pressure in a system is low, sprinkler heads in some of these known systems will not operate to maximum potential and the areas designed to be covered by the particular sprinkler heads will not receive the proper amount of water. Because moisture sensors are generally located adjacent sprinkler heads, it is not unusual for a sensor to receive what appears to be an adequate amount of moisture, whereas the area designed to De covered by the sprinkler heads does not. This results in the water being turned off without adequate coverage to the particular area.
In systems where there are a large number of sprinkler heads on a single line, the ones that are located furthest from the source of water normally receive lesser amounts of water than those closer to the supply, particularly when the pressure is low. This causes the closer sprinkler heads to operate normally, and result in an inadequate amount of water being discharged from the further sprinkler heads, resulting in uneven irrigation.
The present invention represents an improvement over the prior systems by providing a unique moisture sensor which controls pressure at the sprinkler head, which in turn controls the operation of the head to regular the amount of water being discharged. The system includes a unique relative moisture sensor, including a metering chamber having a wicked outlet positioned in the ground. The discharged through the wicked outlet is controlled by the amount of moisture in the ground such that water discharges from the metering chamber at a greater rate when there is little or no moisture in the soil. The discharge is retarded when there is moisture in the soil due to the saturation of the wick, which inhibits the discharge flow. The metering valve is directly connected to a pressure chamber which controls the flow through the spray heads, including a unique pressure sensing arrangement whereby the presence of water in the chamber keeps the valve to the spray heads closed, and release of the water in the pressure chamber allows the spray head valve to open. Therefore, when the ground is moist, water remains in the metering chamber and in turn, remains in the pressure chamber within the valve. When the moisture in the ground dissipates, water discharges from the metering chamber, and in turn discharges from the pressure chamber, allowing the valve to open to permit additional flow.
Among the objects of the present invention are the provision of a sprinkler head system which will operate at its maximum design potential during both normal and low water pressure situations to provide adequate irrigation of a variety of areas covered by the system.
Still another object is the provision of a sprinkler system which is directly controlled by the amount of moisture in the ground.
Still another object is the provision of a sprinkler head system in which individual sprinkler heads may be controlled independently of the others to ensure proper irrigation level.
A further object of the present invention is the provision of a sprinkler head system which operates to prevent both underwatering and overwatering of an area being irrigated. These and other objects will become apparent with reference to the accompanying drawings and specification.